Average age of 80 boys in a class is 15. average age of a group of 15 boys in class is 16 and averag

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The average age of $80$ boys in a class is $15.$ The average age of a group of $15$ boys in the class is $16$ and the average age of another $25$ boys in the class is $14 .$ What is the average age of the remaining boys in the class ?

A

$15.25$

B

$14$

C

$14.75$

D

Cannot be determind

Solution

Total ages of $80$ boys $=15 \times 80=1200$ years

Total age of $16$ boys $=15 \times 16=240$ years

Total age of $25$ boys $=14 \times 25=350$ years Average age of the remaining boys

$=\frac{1200-(240+350)}{80-(25+15)}=\frac{610}{40}=15.25$ years

Standard 13

Quantitative Aptitude

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